1thanks, can we apply bernouli's principle?
IIT 2003>...............Air is blown into a pipe of radius b,with velocity v. After some time the air stops at the end of the pipe and Bubble grows and detaches from the pipe.If surface tension is S, density is K. Find the radius of the bubble thus formed.
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2 Answers
1The bubble will float away only if the normal thrust force on the bubble due to the " blown air " exceeds the force on the bubble due to the excess pressure inside it .
Thrust force per unit area - K v 2
Excess pressure - 4 SR
Hence , K v 2 = 4 SR
Or , R = 4 SK v 2
Interestingly , the result doesn't depend on the radius of the pipe , because I made the assumption that , " b >>> R " . If these two are comparable , then this problem would be a very tough one indeed !